The present invention relates to a fluid dispenser comprising: a fluid reservoir formed with an opening; a fluid dispensing system; and a feed duct connecting the opening of the reservoir to the dispensing system.
Numerous documents are already known that describe fluid dispensers using vibrating membranes to dispense fluid. For example, mention might be made of Documents EP 0 682 570, EP 0 615 470, and EP 0 696 234. In those three documents, the dispensing system used comprises a perforated membrane that is subjected to sustained vibration, e.g. generated by a piezoelectric element. Fluid is in contact with one of the faces of the perforated membrane, and the perforated membrane being caused to vibrate causes the fluid to pass through the holes in the perforated membrane so as to be dispersed in the form of fine droplets of fluid. It is advantageous for the fluid present at the face of the membrane to be at a pressure substantially equal to or slightly lower than atmospheric pressure. In Document EP 0 682 570, the fluid is drip fed to the perforated membrane. Therefore, it is indeed at atmospheric pressure. In Documents EP 0 615 470 and EP 0 696 234, the fluid is fed to the perforated membrane by means of a capillary action feed that is immersed in a reservoir of fluid. To ensure that such feeding by capillary action functions properly, it is essential for the fluid in the reservoir to be stored at a pressure substantially equal to or slightly lower than atmospheric pressure. That problem is not addressed in the two above-mentioned documents.
Document U.S. Pat. No. 5,838,350 even describes a membrane dispenser in which the reservoir is a flexible pouch. However, the deformation of the pouch as the fluid is extracted therefrom generates pressure variations at the membrane.
The present invention proposes to remedy the above-mentioned problem by defining a fluid dispenser advantageously but not exclusively having a vibrating membrane, and in which the reservoir is specially adapted to the fluid being fed at a constant pressure that is substantially equal to or slightly lower than atmospheric pressure.
To this end, the present invention provides a fluid dispenser comprising: a fluid reservoir formed with an opening, the reservoir comprising a deformable flexible pouch in which the fluid is stored at a pressure substantially equal to or slightly lower than atmospheric pressure; a fluid dispensing system including a dispensing outlet; and a feed duct connecting the opening of the reservoir to the dispensing system; wherein the flexible pouch contains a piece of porous material.
The piece of porous material serves to further improve the constancy of the pressure inside the reservoir. It serves as a damping buffer while fluid is being dispensed through the membrane and after it has been dispensed, each time fluid is dispensed. The flexible pouch preferably has no shape memory, nor any significant resistance to deformation, so that its capacity can be modified without significantly varying the pressure inside the pouch. This is not the case with a rigid flask having an air intake, because air then penetrates into the reservoir only at the end of dispensing of the fluid, and therefore suction is generated inside the reservoir. Neither is this the case with a follower piston system that requires significant suction inside the reservoir to enable the follower piston to be returned by suction. All of these problems of pressure variation inside the reservoir are eliminated with a flexible pouch that is freely deformable and in which a piece of porous material is received. At best, each time the flexible pouch is deformed, very slight suction is generated inside the flexible pouch, which is a desired condition to enable a vibrating membrane dispensing system to function properly. It is preferable for the fluid to be subjected to slight suction at the membrane in order to guarantee spraying that is of good quality.
The present invention can be summed up as the synergistic combination of a freely-deformable flexible pouch and of a piece of porous material for containing the fluid to be dispensed, advantageously with a dispensing system having a perforated vibrating membrane.
In addition, the use of a flexible pouch enables the fluid it contains to be preserved well because it is never in contact with the air.
Advantageously, the reservoir further comprises a flexible pouch support to which the pouch is bonded, the opening of the reservoir being formed by said pouch support, and the piece of porous material being secured to said pouch support. In practical manner, the piece of porous material may include a connection end piece engaged in the opening of the pouch support. Preferably, the piece of porous material obstructs the opening. Thus, there is no direct communication between the fluid situated in the empty space inside the flexible pouch and the feed duct. On the contrary, the fluid is constrained to pass through the piece of porous material in order to reach the feed duct. The piece of porous material also makes it possible to guarantee that fluid is present at the opening of the reservoir. Thus, the feed duct is permanently in communication with the fluid. Advantageously, the feed duct is connected to the opening. Preferably, the feed duct obstructs the opening. Thus, the feed duct is connected directly to the piece of porous material, and the fluid inside the fluid-soaked porous material can go directly into the feed duct. Advantageously, the feed duct contains an element made of porous material for conveying the fluid by capillary action from the reservoir to the dispensing system. Thus, there is no discontinuity in the porous material between the reservoir containing the piece of porous material and the feed duct containing the element made of porous material. Thus, it is possible to guarantee permanent and constant feeding with slight suction generated by the deformable flexible pouch.
In a visually attractive embodiment, the dispensing system and the feed duct are mounted in a shell made up of two pieces, advantageously leaving a portion of the reservoir visible.
In a preferred embodiment, the dispensing system comprises a vibrating membrane perforated with holes through which the fluid is dispensed in the form of fine droplets. In which case, the dispensing system may be substantially analogous to the systems described in the above-mentioned prior art documents.